Image forming apparatuses include printers, facsimiles, and copying machines, and more particularly include electrophotographic apparatuses. Recently, an image forming apparatus, wherein process cartridges are used, has been proposed. The process cartridge refers to a unit wherein peripheral members for use with a device such as a photoreceptor, a charger, a developing device, and cleaning device, are integrally installed for each process.
A drum cartridge 52, shown in FIG. 41, and a developing cartridge 53, shown in FIG. 42, are exemplified as those process cartridges. In the drum cartridge 52, a photoreceptor drum 54, a waste-toner transport section 55, and other members are integrally installed into one unit. In the developing cartridge 53, a magnet roller, not shown, a toner cartridge 56, a waste-toner collecting box 57 and other members are integrally installed into one unit. As illustrated in FIG. 40, the drum cartridge 52 and the developing cartridge 53 are removably attached to a copying machine 51. In such a copying machine 51, replacement of certain parts is performed by replacing the corresponding cartridge at one time.
Further, in some of the conventional apparatuses, a main cartridge, wherein a photoreceptor, a charger and a cleaning device are integrally installed, is removable attached to the apparatus, instead of the process cartridges.
By concentrating some parts integrally into each cartridge, it becomes possible to attach and remove parts easily; this simplifies maintenance such as replacement of parts, etc. As a result, the maintenance, which was conventionally performed by specialized engineers, may be also performed by the user.
Here, the service lives of respective parts are different from one another; therefore, in the case of replacing each cartridge at one time as described above, the time of replacement is restricted by the member that has the shortest service life in the cartridge. For example, the photoreceptor drum 54 is most likely to have a shorter service life than the waste-toner transport section 55 in the drum cartridge 52. Therefore, the service life of the photoreceptor drum 54 restricts the time of replacement of the entire drum cartridge 52. Consequently, the waste-toner transport section 55, which would otherwise be continuously used, is also disposed as waste; this results in wasteful use of resources as well as an increase in maintenance cost.
The problem described above is the first problem to be solved by the present invention in connection with the cartridges of the image forming apparatus.
Meanwhile, for example, in dry copying machines, a developing device wherein an electrostatic latent image formed on the surface of the photoreceptor drum is visualized, that is, developed by using developer that consists of two ingredients of carrier and toner, is used in most cases. The image on the surface of the photoreceptor that is visualized by the developer is transferred onto a sheet of copy paper, thereby forming a copied image. In such a developing device, toner is consumed during the developing processes, while carrier remains in the developing device without being consumed. Therefore, the carrier in the developing device gradually deteriorates through stirring processes that are repeatedly carried out. This is because the resin coat layer of the carrier surface tends to come off, and toner tends to adhere to the carrier surface. As the carrier deteriorates, the charging performance of the developer gradually decreases.
In this connection, an apparatus wherein the decrease in charging performance is prevented by supplying developer consisting of a mixture of carrier and toner to the developing device from a developer-supplying container, has been proposed. For example, Japanese Laid-Open Patent Application No. 267683/1987 (Tokukaihei 1-267683) discloses such an apparatus. In the developing device of this type, developer inside the developer tank becomes excessive due to supply of carrier, and overflows from a developer overflow outlet formed in the wall surface of the developer tank. The resulting excessive toner is discharged into a waste-developer container and stored therein. Through these continuous supplying and discharging processes, deteriorated developer contained inside the developer tank is gradually exchanged for newly supplied toner and carrier; this makes it possible to maintain the charging performance and to reduce adverse effects on copied-image quality.
The developer-supplying container and the waste-developer container, which are commonly integrated into one unit, are removably attached to the main body of the apparatus. This arrangement makes it possible to replace both of the containers more easily compared to the case wherein these parts are independently attached to the main body of the apparatus.
The residual toner on the surface of the photoreceptor, on the other hand, is collected by the cleaning device after the developing process, and is housed in a waste-toner container, which is installed inside the cartridge, or which is installed separately from the cartridge.
However, the waste-toner container is installed separately from the developer-supplying container and the waste-developer container that are integrated into one unit; this gives rise to a need to further improve the replaceability of those three containers.
Moreover, in the case where the waste-toner container is installed together with the photoreceptor in the same cartridge, the cartridge needs to be replaced by the new one when the service life of the photoreceptor has terminated. Therefore, the volume of the waste-toner container needs to be set in relation to the service life of the photoreceptor. In this case, the longer the service life of the photoreceptor is, the larger the volume of the waste-toner container should be made. As a result, the size of the waste-toner container tends to make the entire apparatus become bulky.
Furthermore, in the case of the apparatus without such a cartridge, the waste-toner container is independently installed. Here, when the waste-toner container has been filled with toner, the waste-toner container is replaced, or the toner inside the waste-toner container is disposed as waste. Therefore, this arrangement requires a detection means for detecting the situation where the waste-toner container is filled with toner and an informing means for dealing with the situation, thus causing an increase in production cost.
The problem described above is the second problem to be solved by the present invention in connection with the waste-toner container of the image forming apparatus.
Meanwhile, for example, in the case of a copying machine which is capable of full-color copying by installing a mono-color-toner developer tank and a plurality of developer-supplying containers, it is necessary to replace the developer tank and the developer-supplying containers at least in terms of respective colors. Here, each developer tank is forced to contact the photoreceptor drum in order to maintain a predetermined positional relationship between the photoreceptor drum and the developing rollers installed therein. Therefore, upon replacing the photoreceptor drum, it is necessary to remove the developer tanks beforehand. In this case, if each developer tank and each developer-supplying container together with the waste-developer container or the waste-toner container are integrated into one unit, the developer-supplying container and the waste-developer container or the waste-toner container need to be replaced together with the developer tank.
Thus, it has been desired to develop an arrangement which will enable a plurality of containers to be removably attached more easily.
Moreover, Japanese Laid-Open Utility Model Publication No. 8755/1988 (Jitsukaishou 63-8755) discloses a copying machine which is provided with the following means:
(1) a developer tank which is removably attached to a photoreceptor drum in its axis direction; PA1 (2) a clamping means for preventing the developer tank from moving in the axis direction; PA1 (3) a positioning means for positioning the developer tank at a predetermined station in a direction orthogonal to the axis direction; and PA1 (4) a coupling means for releasing the positioning operation of the positioning means in response to the developing-tank releasing movement made by the clamping means, and for allowing the positioning means to perform the positioning operation in response to the developing-tank fixing movement made by the clamping means. PA1 a drum cartridge for housing a photoreceptor drum; PA1 a waste-toner transport unit for transporting toner that has been scraped off the photoreceptor drum; PA1 a developing cartridge for developing an electrostatic latent image that is formed on the photoreceptor drum; and PA1 a toner cartridge which is constituted of a waste-toner container for storing the toner that is transported by the waste-toner transport unit and a developer-supply container for supplying developer to the developing cartridge, both integrally formed into one part, PA1 wherein the drum cartridge, the developing cartridge and the toner cartridge are attached so as to be respectively removable in a first direction, and the waste-toner transport unit is pivotally attached independently from the drum cartridge in such a manner that it allows the drum cartridge to be shifted in the first direction and removed from the apparatus. PA1 a developer tank for storing developer that is used to develop an electrostatic latent image formed on the photoreceptor, the developer tank being arranged so that upon supply of the developer, excessive developer is allowed to overflow therefrom; PA1 a developer-supplying container for storing at least one ingredient that is contained in the developer, and for supplying the ingredient to the developer tank; PA1 a waste-toner container for storing waste toner that has been collected from the surface of the photoreceptor; and PA1 a waste-developer container for storing developer that has overflown from the developer tank, PA1 wherein the three parts, that is, the developer-supplying container, the waste-toner container and the waste-developer container, are integrated into one unit. PA1 a developer tank for storing developer that is used to develop an electrostatic latent image formed on the photoreceptor, the developer tank being arranged so that upon supply of the developer, excessive developer is allowed to overflow therefrom; PA1 a developer-supplying container for storing at least one ingredient that is contained in the developer, and for supplying the ingredient to the developer tank; PA1 a waste-toner container for storing waste toner that has been collected from the surface of the photoreceptor; PA1 a waste-developer container for storing developer that has overflown from the developer tank; and PA1 pressing means for pressing the developer tank toward the photoreceptor drum, PA1 wherein the three parts, that is, the developer-supplying container, the waste-toner container and the waste-developer container, are integrated into one container unit, which is removable in a first direction with respect to the developer tank; the container unit is attached so as to freely move between a first station from which the container unit and the developer tank are removed and a second station providing a predetermined position at which the container unit and the developer tank are attached to the image forming apparatus; and the pressing means presses the developer tank toward the photoreceptor following the movement of the container unit toward the second station, as well as allows the developer tank to separate from the photoreceptor following the movement of the container unit toward the first station. PA1 a shifting member that shifts with the movement of the container unit in a second direction as well as in a third direction that is opposite to the second direction; PA1 a pressing member that moves in a fourth direction so as to press the developer tank toward the photoreceptor as well as moving in a fifth direction so as to separate the developer tank from the photoreceptor in response to the shift of the shifting means; and PA1 an elastic member, installed between the shifting member and the pressing member, for driving the pressing member so that the pressing member is moved in the third direction when the shifting member shifts in the second direction in response to the movement of the container unit in the second station, as well as for releasing the driving of the pressing member so that the pressing member is moved in the fourth direction when the shifting member shifts in the third direction in response to the movement of the container unit in the first direction. PA1 an interlock switch for detecting the operable state of the image forming apparatus; PA1 a covering member for covering the interlock switch when the container unit is not positioned at the second station, and for exposing the interlock switch by retreating when the container unit is positioned at the second station; PA1 a lid for allowing access to the inside of the image forming apparatus; and PA1 a switch operation section, attached to the inner face of the lid, by which the interlock switch is operated upon closing the lid with the container unit being positioned at the second station. PA1 an upper body to which the developer tank and the container unit are attached and which is opened upward so that the inside of the image forming apparatus is exposed; PA1 a locking means for locking the upper body in its closed state; and PA1 a release-restricting means for restricting the locking behavior of the locking means from being released when the container unit is positioned at the first station.
In the above arrangement, however, although consideration is given to an arrangement for removably attaching the developer tank, no consideration is given to an arrangement for removably attaching other containers and like members easily following the removably attaching operation of the developer tank. Further, it is necessary to operate the clamping means only for the purpose of positioning and clamping the developer tank; this increases operations in number that are required upon making tasks such as replacement of the photoreceptor drum, etc., and makes the tasks more troublesome and time-consuming.
The problem described above is the third problem to be solved by the present invention.